Auxiliary contact interlocking device

ABSTRACT

Disclosed is a circuit protector having an interlock arrangement for operating an auxiliary switch when the protector is tripped by an overcurrent but not when the main contacts are manually opened. An interlock plate receives the stepped end of a support arm and normally holds the auxiliary switch in a first condition. Overcurrent tripping rotates the support arm to free the interlock plate, allowing the auxiliary switch to operate. The auxiliary switch is reset through the interlock plate when the main contacts are manually closed.

O United States Patent m 9 [72] Inventors Eiji Shibuya [55] ReferencesCited gam F k v UNITED STATES PATENTS 2,656,439 |0/|953 Gelzheiser337/79 Sawamura. K|taAdach|-Gun, all of, Japan 38 57 6 L 335 1 6 [2 Appl5,840 3, 8,3 6/l9 8 awson I [22] Filed July 29, 1969 PrimaryExaminer-Harold Broome [45] Patented July 13, 197] Attorney-Lc Blanc andShur [73] Assignee Sanken-Alrpax Company Limited Tokyo, Japan ABSTRACT:Disclosed is a circuit protector having an interlock arrangement foroperating an auxiliary switch when the protector is tripped by anovercurrent but not when the main 22 fgggg z gi DEVICE contacts aremanually opened. An interlock plate receives the g stepped end of asupport arm and normally holds the auxiliary [52] U.S.Cl 335/160 switchin a first condition. Overcurrent tripping rotates the l Hlllh 9/24support arm to free the interlock plate, allowing the auxiliary [50]Field of Search 335/160, switch to operate. The auxiliary switch isreset through the inl6l I I, I7; 317/54; 337/79 terlock plate when themain contacts are manually closed.

PATENTEU JUL] 3 Ian SHEET 2 OF 2 FIG. l0

INVENTORS EIJI SHIBUYA TAKESHI KONOMOTO QKIHIRO SA'IAMURA BY ATTORNEYSAUXILIARY CONTACT INTERLOCKING DEVICE This invention is related to ameans of interlocking a set(s) of auxiliary contacts with manual andtripping operations of an electrical circuit breaking device.

With regard to electromagnetic switches capable of interrupting acircuit when an excessively large current flows in the circuit, avariety of devices have heretofore been announced; those of largecurrent interrupting ratings are usually known as no-fuse circuitbreakers, while those of smaller current interrupting ratings, ascircuit protectors.

This invention is generally concerned with a device which belongs to thelatter group mentioned above.

Some types of circuit protectors produced by the prior art incorporate anumber of auxiliary contacts which are operated as the main contacts areeither closed or opened. In these types of circuit protectors, however,auxiliary contacts are made to operate both in the case of the openingof main contacts by a flow of overcurrent (called tripping). In thismanner, it is not possible to discriminate from the operation of theauxiliary contacts whether the circuit protector is opened by hand or byan overcurrent. Therefore, circuit protectors of the prior art cannot beused in such applications as may require generation of alarms only whenthe circuit protectors are tripped by an overcurrent. For disabling theauxiliary contact circuit at the time of the manual opening, circuitprotectors of the prior art require provision of a special,externnlcircuit whi r. disconnects the auxiliary contact circuit fromexternal circuits such as alarm circuits selectively when the circuitprotector is opened by hand. The need of such special cilcuit inevitablyintroduces inconvenience in use as well as complexity in structure,while it incurs an increase in cost.

Among conventional no-fuse circuit breakers of large current ratings,some types include a built-in control circuit which permits operation ofthe auxiliary contact circuit only when the circuit breaker is trippedby an overcurrent. Circuit protectors of small current ratings, however,are generally made small in structure and hence complex in internalmechanism, and also have a relatively weak overcurrent tripping force.Therefore, it has hitherto been extremely difficult to provide circuitprotectors with a special, built-in device which selectively permitsoperation of the auxiliary contact circuit only at the time ofovercurrent tripping.

In view of the foregoing description, it is a general object of thisinvention to solve this problem and provide a new auxiliary contactinterlocking device.

These and further objects and advantages will be more apparent from thefollowing specification, claims and appended drawings in which:

FIGS. 1 and 2 are diagrams illustrating a conventional circuit breakingswitch with a set of auxiliary contacts;

FIG. 3 is a diagram illustrating an embodiment of this invention;

FIG. 4 is an enlarged diagram illustrating in detail only the interlockportion shown in FIG. 3;

FIG. 5 is a diagram illustrating an embodiment of this invention whichis a manually operated position;

FIG. 6 is an enlarged diagram illustrating in detail only the interlockportion shown in FIG. 5',

FIG. 7 is a diagram illustrating an embodiment of this invention whichis in a tripped position;

FIG. 8 is an enlarged diagram illustrating in detail only the interlockportion shown in FIG. 7;

FIG. 9 is a diagram showing only the principal portion of an embodimentofthis invention;

FIG. I0 is another diagram showing only the principal portion of anembodiment ofthis invention.

For better understanding ofthis invention, the structure of aconventional circuit protector having a set of auxiliary contacts willfirst be described in connection with the accompanying drawings or moreparticularly with FIGS. 1 and 2. FIG. I illustrates only the principalmechanism of a conventional circuit protector whose main contacts are ina closed position. In

FIG. 1, a circuit current enters the circuit protector via terminal I,flows through lead 2, trip coil 3, lead 4, contact arm 5, main contact6, and the opposite main contact 7, and finally goes out via a terminal8 into a load circuit. While the circuit current is maintained at anormal level, current is permitted to continuously flow via the circuitprotector. Should an overcurrent flow, the trip coil 3 is energized andopens the closure of the main contacts 6 and 7, thereby protecting theload circuit from being overloaded. The circuit protector shown in FIG.I is under the normal current condition in which the main contacts 6 and7 are closed permitting a circuit current to flow. Both the contact arm5 and a link 23 are pushed upward by the force f, of a spring (notshown) but are held in position by a cam 22. A portion of the cam 22 isengaged and fixed with a pin 25. (Note: This pin is usually called ashearing pin.) If, under this condition, a handle 18 is thrown from thepresent position toward the left in FIG. I for opening the circuitprotector, the handle I8 rotates counterclockwise with a pin 19 as itssupporting point, causing a pin 20 also to rotate counterclockwise or torise with respect to the present position. When the pin 20 is raised,both the cam 22 and a support 2! are also moved upward, because they arecoupled together by the pin 20. On the other hand, a guide pin 26 isprovided at an end of the link 23 and fitted in a portion of the cam 22,while a coupling pin 27 is used to connect the support 21 with the link23. These two pins, 26 and 27, are used to hold the link 23 in place,resisting an upward force f, However, as the cam 22 and hence the link23 move upward, the holding force provided via the pins 26 and 27 willbe removed. When the holding force is removed, the link 23 and contactarm 5 are freed and pushed upward by the force f,, opening the closureof the main contacts 6 and 7.

During the manual operation of the circuit protector, one end of the cam22 remains coupled with a pin 25 and hence all of the support 21, cam22, and line 23 are moved together as a single unit. Although thesupport, cam, and link are permitted to rotate counterclockwise, theyare restrained from drawing a free, large locus, because all three arecoupled together.

Now, the following description applies to the case in which the circuitprotector is tripped by an overcurrent.

When an overcurrent flows through the circuit protector, the trip coil 3is energized and a core 41 attracts an armature 3]. As the armature 31is attracted by the core 41, it rotates counterclockwise with a pin 40as its supporting point while the other end of the armature 31 is raisedwith respect to the present position. The other end of the armature 31then hits one end of a tripping rod 24 situated adjacent to the armature3], providing a counterclockwise torque f, to the tripping rod 24. Undernormal conditions, a clockwise torque f. is applied on the tripping rod24 which then functions to maintain the coupling status of the pin 25and cam 22, preventing a free movement of the cam 22. If the armature 3|hits the tripping rod 24 with a larger torque f, than the torque I.applied on the tripping rod 24, it causes the tripping rod 24 to rotatecounterclockwise, thus disengaging the pin 25 from the cam 22. As thecam 22 is disengaged from connection with the pin 25, the cam 22 isfreed for movement. The force holding the link 23 downward is thusremoved, permitting the link 23 and the support 2! connected togetherwith the link by the coupling pin 27 to rotate counterclockwise by theforce I, applied on the link 23 by a spring (not shown). The contact arm5 connected with the link 23 by a pin 28 is now permitted to trip upwardand to open the closure of the main contacts 6 and 7. In this particularcase, the movement of the support 21 and link 23 is not restricted bythe cam 22 and thus the locus drawn by the support and link as theyrotate counterclockwise should become larger than that exhibited whenthe circuit protector is manually operated. The difference between thetwo loci is utilized in this invention to provide an auxiliary contactinterlocking device.

The operation of auxiliary contacts is now described with reference alsoto FIG. I. In circuit protectors of the prior art, it has hitherto beenthe practice to interlock auxiliary contacts with the tripping operationof main contacts. As shown in FIG. I for example, the contact arm 5 isused to control interlock plate 9 which is free for moving upward ordownward as controlled by the contact arm 5. The interlock plate 9 inturn is pushing a movable rod I downward. While the main contacts aremaking a closure as shown in FIG. I, the movable rod I0 is pusheddownward by the contact arm via the interlock plate 9, which is thendepressing a spring contact 11. Thus, the spring contact II is permittedto keep contact with an auxiliary contact 15. Under this condition, anelectrically through circuit is completed via a terminal I2, the springcontact 11, contact I5, and terminal 13. When the main contacts 6 and 7open the closure, the contact arm 5 will be raised, permitting theinterlock plate 9 to move upward. The force holding the movable rod 10in place is then removed, causing the spring contact II to switch to theother auxiliary contact 16. Thereby, another electrical circuit iscompleted via the ter minal I2, spring contact ll, contact 16, andterminal 14.

As has been described with reference to a specific example, auxiliarycontacts of the prior art are operated every time when the main contactsopen the closure, regardless of whether the opening of the main contactsis made by hand or by tripping, and thus it is not possible todiscriminate from the operation of the auxiliary contacts whether thecircuit protector is tripped by an overcurrent or by hand.

An object of this invention is to provide a means of discriminatingbetween manual tripping and overcurrent tripping in a circuit protector.

Those not mentioned in the foregoing description but shown in FIG. Iinclude: a microswitch assembly I7, a supporting plate 29 whichmaintains many parts of the circuit protector in place, a supportingpoint 30 for the contact arm 5, and a housing 32 which contains theentire mechanism of the circuit protector.

For the purpose of illustration only, the operation of a conventionalcircuit protector has been described with reference to FIG. I. Ofcourse, a circuit protector, to which this invention is applied, shallnot be limited to one illustrated in FIG. I but can be extended to sucha mechanism as shown in FIG. 2. With reference now to FIG. 2, there isillustrated a support 21 which replaces, and provides the same functionas, the cam 22 used in the circuit protector illustrated in FIG. I. Whenan armature 3] hits a tripping rod 24 in the counterclockwise directionat the time of overcurrent, a support 21 is freed from engagement withthe tripping rod 24 and a link 23, and permits the link 23 to trip androtate counterclockwise, thus opening the closure of main contacts 6 and7. 0n the other hand, manual opening of the circuit protector maintainsengagement between the support 21 and the link 23 and thus thecounterclockwise rotation of the jointed unit of the support 2] and link23 draws a rather limited locus as compared to that drawn when thecircuit protector is tripped by an overcurrent. Therefore, by utilizinga difference between the two loci, such a mechanism as illustrated inFIG. 2 can also be used to embody this invention.

Briefly stated, a feature of this invention is to utilize a differencein locus to provide an auxiliary interlocking device as follows: In acircuit protector whose main contacts can be opened either manually orby an overcurrent tripping as mentioned in the foregoing, aspring-loaded plate interlocked with a set(s) of auxiliary contacts isadditionally provided, which will be activated to operate the auxiliarycontacts only when the circuit protector is tripped by an overcurrent.Said springloaded interlock plate is usually held in place by anadditionally installed support arm at all times except when the circuitprotector is tripped by an overcurrent. When the circuit protector istripped by an overcurrent, a specific part of the circuit protectortripping mechanism which draws a unique locus for overcurrent trippingapplies a force to said support arm in order to free said spring-loadedinterlock plate from the existing restraint. Hence, auxiliary contactsare operated by the freed spring-loaded interlock plate. On the otherhand, an arrangement is made in this invention so that, when the circuitprotector is tripped by hand, no force is applied to said support armand hence auxiliary contacts remain deactivated.

Another feature of this invention is to utilize the contact arm, whichhas one of the main contacts at its end, for resetting by hand thecircuit protector from its tripped posi' tion to the normal position.

A further feature of this invention is to utilize the support arm andspring-loaded interlock plate for imparting a controlling force from thecontact arm to auxiliary contacts.

These and other objects and features of this invention will be betterunderstood upon consideration of the following detailed description ofseveral embodiments of this invention with reference to the accompanyingdrawings and more particularly with FIGS. 3 through 10.

FIG. 3 illustrates an embodiment of this invention with its maincontacts being closed. The parts constituting the main trippingmechanism of the embodiment illustrated in this figure are the same asthose illustrated in FIG. 1 and are numbered in the same manner as inFIG. 1, except for some portions that have been omitted for ease ofunderstanding. This omission is also practiced in FIGS. 5 and 7 whichwill be described later.

In the device illustrated in FIG. 3 which is an embodiment of thisinvention, a microswitch assembly I7 has a set of auxiliary contactswhich are to be operated by a spring contact I]. Perpendicularly to oneside of the spring contact II, a movable pin I0 is provided, which ispressed downward by a spring-loaded interlock plate 9. By the force of aspring, the interlock plate 9 tends to move upward but is held inposition by a support arm 35. Therefore, the movable pin 20 keepsdepressing the spring contact ll, having it make contact with anauxiliary contact 15. The support arm 35 is coupled with a supportingplate 29 by a pin 38 together with a spring 37, which therefore tends torotate counterclockwise by the force of the spring 37. Thecounterclockwise rotation of the support arm 35 is however held by theinterlock plate 9 because the support arm 35 and interlock plate 9 arejointed together through a hole 33 made in the interlock plate 9. Thesupport arm 35 can be rotated clockwise only when a clockwise torquegreater than the resisting force by the spring 37 is applied to thesupport arm. Although the support arm 35 is engaged with the interlockplate 9, it is permitted to rotate clockwise because there is providedan open space in the hole 33 toward the clockwise direction of thesupport arm 35 as illustrated in FIG. 4 which is an enlarged diagram ofthe portion in which the support arm 35 is engaged with the interlockplate 9. The top edge 36 of the support arm 35 is the place to be hit bya tripping rod 24 and thus should be placed in a locus drawn by thebottom end of the tripping rod 24. In FIG. 3, the pictures ofa support2|, cam 22, and link 23 are omitted.

Referring now to FIGS. 5 and 6, an operation which will occur when ahandle 18 is thrown by hand from right to left for opening the closureof main contacts 6 and 7 is described. The main tripping mechanism willoperate in an identical manner as described for FIG. I, i.e., as thehandle 18 is rotated counterclockwise, a pin 20 and its associatedportion are also rotated counterclockwise and moved upward with a pin 19as their supporting point. Following the movement of the pin 20, both asupport 21 and a cam 22 (both not shown in FIG. 5) also move upward. Bythe upward movement of these parts, a link 23 (not shown in FIG. 5)together with a contact arm 5 is also moved. causing the main contacts 6and 7 to open the closure. In this operation, attention must be paid tothe relative position of a tripping rod 24. Since no external force isapplied to the tripping rod 24 during this operation, a pin 25 ispermitted to maintain engagement with the cam 22. As has already beendescribed with reference to FIG. 1, the support 21, cam 22, and link 23are thus moved in a rather limited locus and cannot make a largecounterclockwise movement. Therefore, the tripping rod 24 exerts noforce on the top edge 36 of the support 35. For this reason, althoughthe main contacts 6 and 7 open their closure, the support arm 35 ispermitted to maintain engagement with an interlock plate 9 asillustrated in FIG. 6, thus preventing the interlock plate 9 from beingfreed from the engagement. Thereby, the status of auxiliary contactsremains unchanged.

With reference now to FIGS. 7 and 8, the operation of the trippingmechanism in the case of overcurrent tripping is described: When anovercurrent flows through a trip coil 3, a core 41 attracts an armature3|, causing one end of the armature to hit a tripping rod 24 as alreadymentioned for the conventional circuit protector illustrated in FIG. 1.Thus, a pin 25 is disengaged from a cam 22, freeing the cam formovement. As a result, a support 2] and link 23 are also freed fromrestraint imposed by the cam 22 and permitted to rotatecounterclockwise. By the force f, of a spring imparted via the link 23and a contact arm 5, both the support 2| and the link 23 will rotatecounterclockwise, drawing a relatively large locus. The bottom end ofthe tripping rod 24 which is secured to the support 21 by the pin 25strikes the top edge 36 of a support arm 35. If the striking force isgreater than the counterclockwise torque holding the support arm 35 inposition, the support arm 35 will rotate clockwise. By the clockwiserotation of the support arm 35, the step-shaped bottom of the supportarm 35 is disengaged from the interlock plate 9, thus permitting theinterlock plate 9 to trip upward by the force of a spring. The interlockplate 9 is then permitted to move upward as far as either a point atwhich the leg of the support arm 35 fills a coupling hold 33 asillustrated in FIG. 8, or a point at which the interlock plate 9 hitsthe contact arm 5.

As the interlock plate moves upward, a movable pin accompanies theinterlock plate 9 and hence the pressure exerted on a spring contact I]is removed, permitting the spring contact II to switch to an auxiliarycontact 16 by its own spring force. Then, another electrical circuit iscompleted via a terminal I2, the spring contact II, auxiliary contact16, and terminal l4. FIG. 7 illustrates the status of a circuitprotector incorporating an embodiment of this invention at the instantwhen the circuit protector hasjust been tripped by an overcurrent andthe closure of main contacts 6 and 7 have just been opened. If a handlei8 is not held in place by hand, the handle IE will also eventually bethrown to the left automatically following the opening of the maincontacts 6 and 7, and accordingly a tripping rod 24 will also be movedto the same position as it would be located when the circuit protectoris manually opened as illustrated in FIG. 5.

Reference now should be made to FIGS. 9 and 10 for operation andstructure of a support arm 35. FIG. 9 shows a side view of a support arm35 holding an interlock plate 9 in place. The support arm 35 is mountedon a supporting plate 29 by means of a pin 38 and is powered by a spring37. The support arm 35 thus tends to rotate by the force of the spring37 but is held in place by the interlock plate 9. If, under thiscondition, an oppositely directed force greater than this spring forceis applied to the support arm 35, the support arm 35 rotates toward thatdirection and the leg of the support arm 35 is freed from engagementwith the interlock plate 9 and falls into a hole 33. FIG. 10 shows aside view of a support arm 35 whose leg falls into a hole 33.

When the load circuit is restored to normal after the circuit protectoris tripped by an overcurrent, there is a need for resetting the circuitprotector to bring the status of both the main contacts and theauxiliary contacts to normal. It may be possible to reset the auxiliarycontacts directly by hand, but this invention utilizes the movement of acontact arm 5 for this purpose. When the circuit protector is reset byhand (i.e., when a handle 18 is brought back to the normal position),the bottom end of the contact arm 5 moves downward. In this invention,this movement is utilized to push an interlock plate 9 downward untilthe step-shaped end of a support arm 35 engages with the interlock plate9.

When a few embodiments of the invention have been illustrated anddescribed in detail, it is particularly understood that invention is notlimited thereto or thereby and cam be embodies in many other ways. Inthe embodiment of this invention described in the foregoing, thetripping rod 24 is ado ted for striking the support arm 3 In ano herembodiment 0 this invention, for example, a unique hammering part forstriking the support arm 35 may be used and provided directly on eitherthe support 21 or the line 23. In a further embodiment of thisinvention, such an arrangement as either the support or the link itselfstrikes the support are 23 can be realized. In a still furtherembodiment of this invention, the structure of the support arm andinterlock plate can take a different form from that illustrated anddescribed hereinbefore.

The principles of this invention enable circuit protectors of smallcurrent ratings to operate auxiliary contacts only when tripped by anovercurrent, so that the opening of circuit protectors by an overcurrentcan be discriminated from that by hand. Devices incorporating anembodiment of this invention thus do not require an additional circuitfor this discrimination and can be used an a convenient, economiccircuit breaking switch. When the devices are opened by hand, they donot produce alarms because their auxiliary contacts are not operated.Therefore, these devices can be used not only as circuit protectors butalso as conventional on-off input switches, providing an extremelyconvenient means of switching electrical circuits.

What we claim and desire to be secured by United States Letters Patentis:

l. A circuit protector comprising a set of main contacts including amovable contact, a set of auxiliary contacts, a handle, a collapsiblelinkage coupling said handle to said movable contact, said main set ofcontacts being manually opened and closed by operation of said handlewhereby said collapsible linkage follows a first path of movement inresponse to manual operation, overcurrent trip means coupled to saidlinkage for collapsing said linkage to open said main contacts inresponse to an overcurrent, at least a portion of said linkage followinga second path of movement in response to overcurrent tripping differentfrom said first path, an interlock plate operatively coupled to saidauxiliary set of contacts, means resiliently biasing said interlockplate toward said linkage, a support arm coupled to said interlock plateand restraining said plate in a first position whereby said auxiliarycontacts are in a first condition, said support arm including meansspaced from said first path but lying in said second path of movementwhereby said support arm is tripped by said portion of said linkage inresponse to overcurrent tripping to release said interlock plate withsaid auxiliary contacts assuming a second condition.

2. A circuit protector according to claim I wherein said linkageincludes a contact ann carrying said movable contact, said interlockplate being resiliently biased toward said contact arm, whereby movementof said contact arm during manual reclosure of said main set of contactsurges said interlock plate back to said first position to reset saidauxiliary set of contacts.

3. A circuit protector according to claim 2 wherein said support arm isrotatably mounted and includes a stepped end defining a shoulder, saidinterlock plate having a hole freely receiving said stepped end of saidsupport arm, and means resiliently biasing said stepped end of saidsupport arm toward one edge of said hole whereby said interlock plateengages said shoulder when said interlock plate is in said firstposition.

3,593,232 Dated July 13, 1971 Patent No.

Inventoflg) Eij i Shibuya, Takeshi Konomoto, and Akihiro Sawamura It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Column 2 line "line" should read "link-- Column 4, line 31, "pin 20"should read --pin lO--.

Column 4, line 73, "support 35" should read "support arm 35--. Column 5,line 26, "hold 33" should read --hole 33 Column 5, line 28, "plate"should read -plate 9--.

Column 6, line 5, "cam" should read --can-- Column 6, line 6, "embodies"should read --embodied-- Column 6, line 11, "line 23" should read --link23- Column 6, line 13, "support are" should read --support arm-- Column6, line 23, "an" should read --as-.

Signed and sealed this lhth day of March 1972.

(SEAL) Attest:

ROBERT GOTTSCHALK Commissioner of Patents EDWARD M.FLETCHER,JR.Attestingr, Officer "OHM PO-105O (IO-69) USCOMM-DC b0376-P69 i 0.5.r-ovnmazur nmfmc OFFICE: I!!! o-asc-sau

1. A circuit protector comprising a set of main contacts including amovable contact, a set of auxiliary contacts, a handle, a collapsiblelinkage coupling said handle to said movable contact, said main set ofcontacts being manually opened and closed by operation of said handlewhereby said collapsible linkage follows a first path of movement inresponse to manual operation, overcurrent trip means coupled to saidlinkage for collapsing said linkage to open said main contacts inresponse to an overcurrent, at least a portion of said linkage followinga second path of movement in response to overcurrent tripping differentfrom said first path, an interlock plate operatively coupled to saidauxiliary set of contacts, means resiliently biasing said interlockplate toward said linkage, a support arm coupled to said interlock plateand restraining said plate in a first position whereby said auxiliarycontacts are in a first condition, said support arm including meansspaced from said first path but lying in said second path of movementwhereby said support arm is tripped by said portion of said linkage inresponse to overcurrent tripping to release said interlock plate withsaid auxiliary contacts assuming a second condition.
 2. A circuitprotector according to claim 1 wherein said linkage includes a contactarm carrying said movable contact, said interlock plate beingresiliently biased toward said contact arm, whereby movement of saidcontact arm during manual reclosure of said main set of contacts urgessaid interlock plate back to said first position to reset said auxiliaryset of contacts.
 3. A circuit protector according to claim 2 whereinsaid support arm is rotatably mounted and includes a stepped enddefining a shoulder, said interlock plate having a hole freely receivingsaid stepped end of said support arm, and means resiliently biasing saidstepped end of said support arm toward one edge of said hole wherebysaid interlock plate engages said shoulder when said interlock plate isin said first position.